Automatic traffic control system



ct. 4, 1938. s, CQRQTH 2,131,818

AUTOMATIC TRAFFIC CONTROL SYSTEM I Filed Feb. 19, 1936 2 Sheets-Sheet 1J7 JZ 6 BY myam l ATTORNEY-S s. c. ROTH AUTOMATIC TRAFFIC CONTROL SYSTEMOct. 4, 1938.

Filed Feb. 19, 19:56 2 Speets-Sheet 2 ATTORNEYS Patented Dot. 4-, 1938ATENT FFQ AUTOMATIC TRAFFIC CONTROL SYSTEM Samuel C. Roth, Allentown,Pa., assignor to Automatic Signal Corporation, East Conn a corporationof Delaware Norwalk,

Application February 19, 1936, Serial No. 64,771

" 1 Claim. 1 (01. 177-337) This invention relates to electricallyoperated traffic sgnal lights and has for an object to provide anautomatic signaldevice of the stop and go,

or stop, caution, and go type capable of adjusting 5 itself to varyingconditions of trafiic at all timesa A further object is to provide adevice of this character adapted" to be installed at intersections wheretraffic is unequally divided and provide positive safety to vehiclesdesiring to cross the 1 main highway. v

A further object is top-rovide a device of, this character which will socontrol traffic that the traffic on the main highway will haveuninterrupted right of way as long as no vehicles appear on the crossroad to contestright of way.

A further object is to provide magnetically operated switches,responsive to cams, or contacts on the program control rotor, and aswitch operated by Vehicles on the cross road, tooperate the traificsignal on the main highway as an ordinary stop and go signal light aslong as there are vehicles on the cross road to cross the intersection,and to maintain the trafiic signal continuous as a go signal for trafficon the main highway when no vehicles are on the cross road, thuspreventing the unnecessary interruption of the main highway traffic by astop signal when no traffic appears on the cross intersection.

With the above and other objects in View the invention consists ofcertain novel details of construction and combinations of partshereinafter fully described and claimed, it being understood thatvarious-modifications may be resorted to within the 'scope of theappended claim without departing from the spirit or sacrificing any ofthe advantages of the invention.

In the accompanying drawings forming part of this specification,

Figure 1 is a diagrammatic view of trafiic signal apparatus constructedin accordance with the invention and showing the motor circuit open tomaintain the green or go light continuously on' the main highway.

Figure 2 is a view similar to Figure 1 but showing the motor circuitclosed to turn the rotor and the upper magnetically operated switch inopen position thus to operate the device as a continuous stop and gsignal of the conventional type.

Figure 3 is a view similar to Figure 2 but'showing the upper switch ofthe pair of magnetically operated switches in closed position to permitstopping of the program control rotor by cam 25 when one revolution ofthe rotor has been completed.

Figure 4 is a diagrammatic view showing how certain camsfon the programcontrol rotor close associated switch contacts. 1 V

Figure 5 is a diagrammatic view showing how another cam on the programcontrol rotor closes associated switch contacts. 5

Figure 6 is a diagrammatic view showing suggested arrangement of thesignal apparatus" at an intersection of a main highway and a cross road.

Referring now to the drawings in which like characters of referencedesignate similar parts in the various views, 8 designates a traificsignal of the type adapted to indicate a go or green signal 9 on themain highway simultaneously with a stop or red signal It) on theintersecting cross 1 5 road and vice versa. Vehicle operated switches Hare disposed. on the cross road in the path of vehicles approaching theintersection'from either direction and these switches are shown as thetype adapted to be closed by contact with a vehicle passing thereoveralthough any preferred type of vehicle operated switch may be employed.

Assembled with the traflic signal 8 are a pair of opposedelectro-magnets l2 and Hi and between the poles of the magnets there ismounted an armature M which is magnetically attracted by one or theother of the magnets to open and close a switch l5 which controls themotorcircuit of the trafiic signal. The switch l5 may be a single throwswitch of the snap type adapted to be yieldably held at either limit ofits movement, at one limit of its movement engaging a switch contact [6in the motor circuit, shown best in Figure 2. l

When the vehicle operated switch H is closed by a vehicle passingthereov-er when approaching the intersection, a circuit H is closedthrough the magnet 53 which is thus energized to attract the armature l4and close the switch It in the circuit E8 of the traffic signal motorIS. Themotor ro- .40 tates the program rotor 20 through a worm 2i andworm gear 22 to set in motion the program control cams 23.

The program control cams operate in the usual manner to close switchcontacts 24 in the signal light circuits in sequence to first change thesignal to caution or amber for the main highway. Then after an'intervalthe signal will be changedto go or green for the cross road andsimultaneously to stop or red for the main highway. After anotherinterval the signal will change to caution for the crossvroad andthereafter to stopor red for the-cross road and simultaneously to go orgreen for the main highway.

The latter or go signal for the main highway will remain continuous aslong as no other vehicles appear on the cross road at the intersectionand this is accomplished'by stopping the rotor at the end of onerevolution by means of a cam 25 on the program control rotor. The cam isdisposed to affect contact 26 preferably at the end of the predeterminedgo period for the main highway and closes switch contacts 26 in acircuit 21 which energizes the electro-magnet I2. When the magnet isenergized it attracts the armature I4 to open the switch I5 which breaksthe motor circuit, as shown in Figure 1. Thus the rotor will stop at apoint which will give a cross lane vehicle a favorable light withoutdelay.

It is essential that means be provided whereby a late arriving vehicleon the cross road will not be trapped at the intersection if the signalis about to change against it. For this purpose a pair of opposedelectro-magnets 28 and 29 are assembled with the trafficsignal andbetween the poles of the magnets there is mounted an armature 30 whichis magnetically attracted by one or the other of the magnets to open orclose a switch 3! in the circuit 27. The magnet 28 is connected inseries with the vehicle operated switch II and in parallel with themotor circuit closing magnet I3, as shown at 32. The magnet 29 isconnected in circuit 33 with a pair of switch contacts 34 which latterare in the path of a cam 35 on the program control rotor 29. The cam 35is disposed to affect contact 34 at or near the end of the go period forthe cross road, or at the beginning of the caution period that follows,so that a late arriving vehicle will command the right of way regardlessof its time of arrival, The magnet 28 should be more powerful than themagnet 29 in order to assure opening of the circuit 21 in the event thatboth magnets 28 and 29 are energized simultaneously.

When a late arriving vehicle that is, one arriving just as a change ofsignal is about to take place, passes over the vehicle operated switchII it will be seen that the circuit through the magnet 28 will be closedand the magnet thus energized attracts the armature 30 to open theswitch 3| in the circuit 2! which controls the motor stoppingelectro-magnet I2. Consequently, when the advancing cam 25 closes thecircuit 21 at the contacts 26 and magnet I2 cannot be energized to openthe switch I 5 and stop the motor since its circuit 27 is open at theswitch 3|, as shown in Figure 2. Thus the program control rotor mustcontinue to another revolution during which time the late arrivingvehicle may proceed safely across the intersection under the protectionof the green or go, light of the cross road.

When the cam 35 subsequently closes the contacts 34 the magnet 29 willbe energized to close the switch 3| which controls the circuit 21 sothat in the event of no more trafiic appearing on the cross road, whenthe cam 25 next moves around into circuit closing position to close thecircuit 21 at the contacts 26 the magnet I2 will be energized to openthe switch I5 and break the motor circuit to stop the motor.

From the above it will be apparent that a vehicle on a cross roadapproaching a main highway intersection will always command a go signaland yet grant the traific on the main highway a sufiicient go intervalto avoid unnecessary delay for traific on the main'highway.

From the above description it is thought that the construction and.operation of the invention will be fully understood without furtherexplanation.

What is claimed is:

In a trafiic control system of the class described, a program controlrotor, an electric motor for driving the rotor. a motor circuit whichwhen closed energizesthe motor and when opened reenergizes the motor, aswitch in the motor circuit, opposed electro-magnets one of which closesthe switch and the other of which opens the switch, a vehicle operatedswitch connected in circuit with the switch closing electro-magnet,switch means operated by the rotor and controlling the electro-magnetwhich opens the motor circuit switch to normally confine the rotor to asingle revolution; and means for permitting the rotor to continuethrough more than one revolution when the vehicle operated switch isactuated just as a change of signal is about to take place comprising acircuit, a switch in said circuit, opposed electro-magnets one of whichcloses the switch and the other of which opens the switch, theelectro-magnet which opens the switch being connected in series with thevehicle operated switch and being connected in parallel with theelectro-magnet which closes the motor circuit switch, switch contacts insaid circuit, the other of the electromagnets being connected in serieswith the switch contacts, and a cam on the rotor for closing the switchcontacts, coasting of the motor permitting the rotor to movesufliciently to disengage said cam from said switch contacts todeenergize said electromagnet which opens said switch.

SAMUEL C. ROTH.

, CERTIFICATE 0F CORREGTION. Patent No. 2,151,818. October h, 1958SAMUEL c. ROTH,

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows: Page 1,first column, line 2, for "sgnal" read signal; page 2, first column,line L 9, for "and magnet" read the magnet; same page, second column,line 26-27, for "re-energizes" read de-energizes; and that the saidLetters Patent shouldbe read with this correction therein that the samemay conform to the record of the case in the Patent Office.

Signed and sealed this Zhth day of January, A, D. 1959..

Henry Van Arsdale (Seal) 7 Acting Commissioner'of Patents.

